Correlation of carotid artery disease severity and vasomotor response of cerebral blood vessels.

We assessed reactivity of cerebral vessels on hypercapnia in patients with carotid occlusive disease. The effects of vascular risk factors on carotid atherosclerosis and vasomotor reactivity (VMR) of cerebral arterioles were also examined. Patients (n = 50) with carotid stenosis (≥30% in 1 or both sides) were included; 30 patients acted as controls. Hypertension, hyperlipidemia, diabetes, cardiac diseases, inflammation, and smoking were recorded. Vasomotor reactivity was assessed with the apnea test by transcranial Doppler ultrasonography and estimated by flow velocity changes in the middle cerebral artery before and after hypercapnia induction. Vasomotor reactivity was defined by the breath holding index, and values under 0.69 were considered critical for VMR impairment. Vasomotor reactivity reduction was significant (P = .004) in patients with severe carotid stenosis (>70%) and with symptomatic carotid disease (P < .05). The risk factors did not significantly influence VMR reduction. Severe carotid stenosis impairs VMR and may increase the risk of stroke, especially in symptomatic patients.